pairs_signal

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Description adds critical context: 'PAID ONLY — no free tier' beyond annotations (readOnlyHint, idempotentHint, destructiveHint). It also details the return values, which helps the agent understand behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences: first states identity, second usage, third outputs. No wasted words, front-loaded with key information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, description explains return values. It covers required inputs and usage. Minor gaps: does not mention min items constraint (20) explicitly nor significance parameter options, but schema fills those.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 80%, so baseline is 3. Description adds value by summarizing the output and reinforcing required inputs ('Provide two price series'). It does not repeat schema but complements it.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Description clearly states 'Complete pairs trading signal' and lists all components (cointegration, Hurst, z-score, half-life, hedge ratio). It explicitly says 'Replaces 4 individual calls', distinguishing it from sibling tools like stats_cointegration, stats_hurst-exponent, stats_zscore.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Description says 'Use when analyzing a pairs trading opportunity' and 'Provide two price series'. It contrasts with individual calls by noting it combines them. However, it does not explicitly state when not to use or mention alternatives beyond the replaced calls.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.